New carboxy-functionalized terpyridines as precursors for zwitterionic ruthenium complexes for polymer-based solar cells

New carboxy-terpyridines selectively functionalized at the 4-, 4′- and 4″-positions were prepared in a three-step procedure with good yields using the Kröhnke reaction followed by saponification. Their complexation with ruthenium led to symmetric and unsymmetric terpyridinyl zwitterionic complexes.